This study evaluated the impact of iron-fortified flours in the prevalence of anemia and hemoglobin levels of pregnant women. This transversal cross-sectional study was developed at a Health Center School in São Paulo - SP, Brazil. Data, collected from September to December of 2006, were obtained from 750 pregnant women's medical records and discriminated into two groups, before and after fortification: non-fortified and fortified. Pregnant women with hemoglobin levels lower than 11g/dl were considered anemic. Data were submitted to multiple regression analysis. Anemia affected 9.2% and 8.6% of pregnant women, before and after the fortification, respectively (p>0.05). Multiple analysis indicates no statistical difference in the mean hemoglobin levels between the groups (p=0.117). The results indicated a low prevalence of anemia and similar hemoglobin levels between the groups, which probably did not allow for demonstrating the effect of flour fortification.